Influence Of Electric Field Strength Research Articles

Analytical determination of the emitter saturation current in ultra-shallow silicon junctions

Simple analytical relations expressing the influence of electric field strength E prevailing in the heavily-doped quasi-neutral layer of ultra-shallow (x j = 01 to 0.3 μm) silicon junctions on the emitter component of the reverse saturation current density J 0 are obtained. It is shown physically and is demonstrated mathematically that, owing to the peculiarities of such junctions, an additional field-based current term appears in the Shockley relation for the emitter component of the saturation current. For the usual values of drift velocities encountered in the heavily-doped layer of ultra-shallow junctions, the field-based term enhances substantially the emitter component of the saturation current. The particular forms of the analytical expression obtained for different practical cases of interest are detailed. The electric-field-free case is also investigated, and simple analytical expressions for emitter saturation current are derived as a function of practical values of the surface recombination vel...

Continuous Separation of Proteins by Free‐Flow Zone Electrophoresis

AbstractFree‐Flow Electrophoresis is a continuous technique for the separation of biological molecules and particles on a preparative scale. In the technique of Free‐Flow Zone Electrophoresis, an electrolyte with a certain pH and conductivity is continuously admitted in a laminar flow at the top of a rectangular electrophoresis chamber (50 cm x 10 cm x 0.05 cm on the Bender and Hobein VAP‐22 machine). A stream of sample is also injected continuously into the electrolyte flow. An electric field transverse to the electrolyte flow separates the sample according to differences in electrophoretic mobility. The separated products are collected by 90 output tubes at the lower end of the chamber. Free‐Flow Zone Electrophoresis has been used for throughput studies on a mixture of model proteins and for the separation of enzymes in Candida boidinii crude extract. Simultaneous separation of proteins, cell particles and debris was obtained. We have looked at the influence of electric field strength (100 – 150 V/cm), buffer residence time in the chamber (2 – 5 min), sample flow rate (1.5 – 6 ml/h) and sample concentration (2.5 – 40 mg/ml) on separation resolution, peak sharpness and skewness and throughput. Qualitative explanations for observed phenomena have been given. For throughput studies, multiple injections of the sample into the chamber were used. A throughput of 500 mg protein per hour was obtained. Other Free‐Flow techniques i.e. Free‐Flow Isoelectric focusing, Isotachophoresis and Field‐Step Electrophoresis can also be implemented on this electrophoresis apparatus.

Ionic current study in thermally grown silicon dioxide films on polycrystalline silicon

The ionic currents in thermally grown silicon dioxide films (PSD) between polysilicon (PS) are investigated by thermally stimulated polarization (TSPC) and depolarization (TSDC) currents and triangular voltage sweep (TVS) techniques. A mixture of dry oxygen and HCl (0, 4, 6, and 8 vol%) is used for oxidation. It is found that the ionic charge is situated near both the PS–PSD interfaces on ionic traps. The influence of electric field strength, oxidation time, and oxidation atmosphere is established. The results are discussed using the PS–PSD interface roughness model. [Russian Text Ignored]

Electric conductivity of compressed copper powder. Ageing and influence of electric field strength

The conductivity of copper powder can be characterized by the initial conductivity κ 1 at low pressure, the critical pressure p c, where the conductivity rises steeply, and the final conductivity κ 2 at high pressure. The conductivity has been measured in the pressure range of 1 to 200 MPa, applying low-frequency a.c., during a period of 5 years. Ageing results in a marked increase of p c and κ 2. In spite of this, the initial conductivity κ 1 depends above all on the electric field strength. It has been measured in the range of 3 to 145 V/cm, followed by a conductivity rise of more than 3 decades. The field influence proceeds in two steps: first a nearly reversible increase of a factor 2; second, after a breakthrough, an irreversible increase, limited only by the temperature limits of the insulating press tool. Local temperatures of more than 250°C have been evaluated.